It is known that organic semiconductors can be chanced as regards their electrical properties, especially their electrical conductivity, as is also the case with inorganic semiconductors such as silicon semiconductors. An elevation of the conductivity, which is rather low at first, is achieved here by the producing of charge carriers in the matrix material, as well as a change in the Fermi level of the semiconductor according to the type of the used dopant. A doping results here in an elevation of the conductivity of the charge transport layers, which reduces ohmic losses, and in an improved transfer of the charge carriers between contacts and organic layer.
Inorganic dopants such as alkali metals (e.g., cesium) or Lewis acids (e.g., FeCl3) are mostly disadvantageous in organic matrix material on account of their high coefficients of diffusion, since the function and stability of the electronic components is adversely affected. Furthermore, the release of dopants via chemical reactions into the semiconductive matrix material in order to make dopants available is known. However, the reduction potential of such released dopants is often not sufficient for various instances of application such as, in particular, for organic light-emitting diodes (OLED). Furthermore, further compounds and/or atoms, for example, atomic hydrogen, are produced in the release of the dopants, which affects the properties of the doped layer and of the corresponding electronic component.
The acceptor-like material can also be used as hole injection layer. Thus, for example, a layered structure anode/acceptor/hole transporter can be produced. The hole transporter can be a pure layer or a mixed layer. In particular, the hole transporter can also be doped with an acceptor. The anode can be ITO, for example. The acceptor layer can be 0.5-100 nm thick, for example. In one embodiment the acceptor layer can be doped with a donor-like molecule.
Square planar transition metal complexes are known, for example from the WO 2005/123754 A2, that can be used in a great plurality of electronic applications, for example, inactive electronic components, passive electronic components, in electroluminescence devices (e.g., organic light-emitting diodes), photovoltaic cells, light-emitting diodes, field effect transistors, photo transistors, etc.) The use of the described square planar transition metal complexes is indicated as charge transport material.
The present invention has the objective of making novel square planar transition metal complexes in which their use results in improved organic semiconductor matrix materials, charge injection layers, electrode materials and storage materials, in particular in electronic or optoelectronic components, in comparison to the state of the art. In particular, the transition metal complexes should have sufficiently high reduction potentials, not have disturbing influences on the matrix material, and make available an effective elevation of the charge carrier number in the matrix material, and be able to be handled in a comparatively simple manner.
Further objectives of the present invention reside in making available organic semiconductive materials and electronic components or optoelectronic components as well as in making available possibilities for using the transition metal complexes.